Exporting Pokemon via "Code Generator" with nonspecified PID results in all having the same PID

I am trying to create a number of Gen 5 pokemon with nonspecified PID and exporting them via the Code Generator ----> Selected Pokemon -----> Generate ----> Export. Pokegen instead of creating a PID for each one of them, creates one PID and assigns it to all of them. I can verify this by exporting 5 of them at once from one pokegen instance, and pulling each one of them back into another instance Pokegen via the "Extract Pokemon from code", and they all have the same PID. I then re-export them from the first, and then back into the second, and they all once again have the same PID that is different from the first.

Is this intended behavior? Will I need to export them one at a time if I do not specify PID? Is there some way to force it to generate a gen 5 PID before export?

Using Pokegen 3.1.13 which I believe to be the latest.